Vehicles, such as automobiles and trucks for example, include an axle assembly that transmits rotational energy developed by the vehicle engine to the wheels. The axle assembly will typically include a housing having a differential gear set. The differential gear set includes a planetary gear train that allows the wheels of the vehicle to turn at different rotational speeds. This allows an outer wheel to rotate faster than the inner wheel during a turn.
In these assemblies, there are a number of locations where the shafts need to be coupled so as to transmit rotational energy from one component to another. One way shafts are coupled is by the use of a spline. A spline is a type of keyed fitting where one of the components includes a groove and the other component includes a projection or key that fits within the groove. The interaction of the projection with the groove transmits rotational energy. In vehicles, it is desirable to maintain a tight or interference fit between the projection and the groove to avoid excessive backlash, which can cause undesired noise. Commonly, vehicles will use helical splines where at least one of the groove or projection will have a helical angle. While helical splines perform well and with low backlash, the cost of manufacture is higher and the stress distribution may not be as desired.
Accordingly, it is desirable to provide a shaft coupling arrangement that improves the contact stress distribution and facilitates assembly with improved manufacturability.